Fanfold sheet refers to a continuous sheet having spaced apart transverse perforations which enable the sheet to be accumulated as a stack by zig-zag folding of the sheet. Such sheet is also variously referred to as fanfold printed forms, and the individual segments are referred to as pages or forms. Typically, when a fanfold sheet issues in shingled fashion from a machine, such as a folder or a printer, segments of the sheet must be gathered together as vertical stacks so they can be either transported or further processed. For instance, the sheet may be subsequently fed to a binder, or other finishing machine. Typical fanfold sheet finishing processing machines are adapted to draw fanfold sheet from stacks which are "normally oriented". That is, the sheets are parallel to the floor or earth surface, and the stack axis is by definition normal to the floor.
In one of the simpler manual ways of effecting such a process, an operator will pick a spot along the length of the shingled sheet issuing from the source device, and tear the sheet at a perforation to create a separate segment of sheet comprised of a desired number of pages. Then, the operator will manually gather together the segment of sheet by laterally pressing it, to form the sheets into a stack "on edge". Next, the operator will press the ends of the stack toward each other, pick the stack up from the work surface while rotating it to a vertical position, and then put the stack onto a dolly, pallet or the like, for transport to the finishing machine.
Gathering shingled sheets into stacks by means of machines is something that has been addressed in the prior art. For instance, Fernandez-Rana et al. in U.S. Pat. No. 3,887,088 describes apparatus for forming a vertical stack of signatures (i.e., folded newspapers) which are delivered to the apparatus in shingled fashion. The apparatus comprises a tilting table which is loaded with signatures by belts running alongside the tilting table.
Crowley in U.S. Pat. Nos. 5,630,780, 5,399,143, and 5,273,516 discloses apparatus and method which aid in accomplishing the desired result for fanfold sheet. The patents describe how fanfold sheet moves from the output of a folder onto an in-line tilting table. When sufficient sheet has been accumulated on the flat surface of a tilting table, and manually pushed into a stack by the operator, a door or gate rises at the input end of the table. The table is tilted to make the table surface vertical, and to cause a stack to be gathered and supported on the surface of the gate. A separate device such as a dolly, is positioned under the gate of the vertically tilted table; and when the gate is retracted, the stack drops onto the top of the dolly, so it can be moved elsewhere. During those steps, a flap at the end of the output conveyor of the source device rises up to block the flow of shingled sheet, preventing it from falling onto the floor.
By design of the Fernandez-Rana and the Crowley devices, when the vertical stack is formed, the pages of the stack are in a pre-determined orientation, relative to the sequence in which the sheet/signatures issue from the source device. In particular, in the Crowley device, when the stack is rotated, the first part of the sheet from the source (designated "A") is at the top of a vertical stack. This is the so-called A-Z orientation. In the Fernandez-Rana device, the opposite, or Z-A orientation, is effected. What an operator may desire with respect to stacking orientation can depend on what the subsequent processing machine demands. In general, in the prior art devices it is either not feasible or difficult for the operator to alter the stack orientation.
The present invention seeks to accomplish the same general goals as the prior art manual and machine methods, but with a device which has advantages in cost or performance over those.